Question

A.

A circle with a radius of 0.3 meters is placed in the x-y plane in a magnetic field directed in the -z direction. It is wound once and its resistance is 6 Ohms. The initial magnetic field is 0.7 Tesla. The magnetic field is then changed in 0.4 s and the average induced current is 0.04 amps running counter-clockwise. First, find the final magnetic field to needed to induce this average current.Then, the magnetic field (still in the -z direction) is held constant at the value of the final magnetic field that was just found. Then, the wire is reshaped into a square that is wound once in a time of 0.007 seconds. If the resistance does not change, what is the average induced current, in amps, when the wire changes shape? If it's clockwise include a negative sign.

B.

A circular coil with a radius of 0.3 meters wrapped 21 times is spun at a frequency of 36 Hz in a uniform magnetic field to form a generator. It is then connected to the primary transformer. The primary side has 33 turns and the secondary side has 11 turns. The maximum secondary current is 6 amps and the resistance of the coil on the primary side is 3 Ohms. What is the amount of the magnetic field in the generator in milli-Tesla?

Answer 1